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Technology These particulates are so small and fissured that they provide a ready carbon source to the many microorganisms within the waste stream and sludge. In this case, criteria were carefully taken into account to ensure that the final design was practical in every sense to address the everyday problems encountered in the removal of FOG deposits. The actual sites of deployment of these devices were to be grease traps and lift stations, but other sites might be used from time to time — especially wastewater treatment facilities. To these ends, designers determined that the most important criteria to address were sizing with respect to air/wastewater movement and aeration; operational costs with respect to maintenance, parts replacement, and accessibility; and operator safety with respect to change-out, cleaning, and electrical issues. This particular technology, developed by DO2E, is unique from several perspectives: There are no moving parts (they are all essentially modified air-lift devices); they are constructed of high-grade, noncorrosive material; and the electrical systems employed, as well as the blower systems, are removed from the "business end" of the devices for improved safety. They operate from a remote blower that provides high-volume, low-pressure air through a central manifold containing a multitude of air outlet orifices of specific sizing that enables a maximum air-lift effect and an air-exchange aeration (oxygenation) effect as well. The Venturi effect formed draws wastewater and its fluid column through inlet orifices, which configuration are quite large. As the fluid is accelerated Internalcabinet control up this pathway, entrained solids are impacted at high velocity against fixed concentric edges and blades at the top of the device and thereby broken down into much smaller fragments. This mixture is repeatedly recirculated as the fragmentation results in ever smaller particles being realized. These particulates are so small and fissured that they provide a ready carbon source to the many microorganisms within the waste stream and sludge. This is why these devices are so efficacious in destroying FOG deposits and preventing their reformation. Data have been collected showing that these FOG deposits do not re-form, even in force mains that are miles long. Simple experiments can readily affirm this, but municipalities must rely on actual results from the 42 wateronline.com ■ field for their decision makers in this regard. A primary design objective has been to make these devices as efficient as possible, and to that end the designers have provided a three-phase power capability with the larger units, as well as providing specific units for differing voltages (115V, 240V, 480V, 600V) and differing frequencies (50 Hz or 60 Hz), so that these units may be used in different electrical systems worldwide. Other specialized requirements may also be fabricated as necessary for a particular application. The actual impact on most wastewater collection and treatment systems is that the use of these digesters expands the functions of the collection system as a pretreatment component of the entire wastewater treatment system. This occurs as a result of lowering the BOD (biochemical oxygen demand)/COD (chemical oxygen demand) challenge to the waste treatment facility, as well as by changing the operational influent flow to assist in the elimination of blankets and rafts of paper products that are a major problem of FOG buildups. This, in fact, reduces the loading on influent screening requirements and subsequent buildups on any of the aeration diffusers employed in the waste treatment plant. The technology provided by these digesters enables both the operational personnel as well as the design engineers to practically eliminate the of 2-HP digester impact of FOG deposits on operations. And all of this is "on the cheap." Water Online The Magazine Douglas D. Sunday is an experienced water and wastewater Class A operator in Florida for the past 40 years. Dr. J.H. Wakefield has been a consulting analytic chemist and environmental/materials engineer for more than 30 years.